Why Turning Off Lights Is Important
Many people believe that turning off lights is important to save energy and reduce the electricity bill. In fact, rapidly switching light bulbs on and off actually lowers the operating life of any type of bulb.
Truelove et al.  found that participants preferred turning off lights above many other pro-environmental behaviors, including improving light bulb efficiency.
From an environmental standpoint, turning off lights conserves energy. This reduces the demand for power which helps conserve finite natural resources such as trees, coal, and oil. It also helps reduce greenhouse gas emissions which contribute to climate change.
For example, one 40-watt light bulb switched off for an hour will save.06 kilowatt hours of electricity. To determine how much that is worth, simply look at your most recent electric bill, find out what the cost per kilowatt hour is, and multiply by the number of hours the light was turned off.
Interestingly, when participants were asked to recommend the single most effective thing they currently do or could do to save energy, turning off lights was by far the most popular answer. However, replacing inefficient bulbs with efficient ones would actually be more effective for saving energy than simply turning off the lights. These two behaviors should be promoted simultaneously to maximize effectiveness.
Aside from the obvious benefits to the environment, turning off lights is also one of the best ways to conserve energy and save money on electricity bills. Whether the lights are on or off, they’re still sucking up electricity. The more you keep them off, the less you’ll pay each month on your electricity plan from electricity retailers.
The amount of electricity you suck per light bulb depends on the type of bulb and how often it’s used. Incandescent bulbs, for instance, are relatively inefficient and only about 10%-15% of the energy they consume results in light. On the other hand, halogen and energy-efficient compact fluorescent or light emitting diode (LED) bulbs use far less energy than incandescents.
When calculating the cost-effectiveness of keeping a light on, you’ll want to take into account your electricity price per kilowatt hour, which can be found on your most recent electric bill. Generally speaking, you’ll save money by keeping a light off for an hour or more.
In addition to energy savings, turning off lights can help you sleep better. Studies have shown that light exposure at night can inhibit the brain’s ability to reach the deepest stages of sleep, which has a range of negative health consequences.
Incandescent and halogen bulbs are the least energy efficient, with 90% of their electricity being given off as heat and only 10% resulting in light. Turning these off whenever you’re not using them can save a lot of energy, especially when compared to more energy-efficient compact fluorescent lights and light emitting diode bulbs.
Some people worry that switching off lights can use more electricity, since some types of bulbs need a little extra power to start up. However, this “inrush current” only lasts for 1/120th of a second and uses the same amount of energy as only a few seconds of normal operation. In fact, in a study of 74 pro-environmental behaviors, participants ranked turning off the lights as being the lowest in financial and behavioral cost . A habit of turning off lights can go a long way to saving money and energy.
Turning off lights is one of the easiest ways to protect the environment. This simple act reduces carbon dioxide emissions, which contribute to global warming. It also helps extend the life of light bulbs. All bulbs have a nominal or rated operating life, which is reduced the more often they are switched on and off.
In fact, turning off lights can significantly prolong the lifespan of incandescent light bulbs. This is because the light bulb uses 90% of its energy for heating, while only 10% results in actual lighting. It is even more important to switch off lights when not in use for other types of bulbs, such as halogen and compact fluorescent lamps (CFL) or LEDs.
When participants were asked to rank 74 pro-environmental behaviors on two dimensions—cost and environmental impact/savings—turning off the lights was one of their top three choices, along with recycling and switching to energy efficient light bulbs. This indicates that turning off the lights is still a popular and effective way to conserve energy.